Light guide plate is one of key components in a backlight module of a LCD display, mobile phone, digital camera and illumination etc. Currently, the method for manufacturing the light guide plate can be divided into printing and non-printing. In printing, a printing material which is highly astigmatic, such as SiO2 and TiO2 etc., is distributed properly at a bottom surface of the light guide plate. Due to properties of light absorption and light diffusion of the printing material, internal transmission induced by optical total reflection is broken up, and the light is emitted from the front face and distributed evenly at a light emitting area. In non-printing, a molding member having a predetermined pattern is prepared first, and the pattern is formed on the light guide plate via injection molding, and the light is guided by the pattern which is distributed evenly on the light emitting area. Currently, the light guide plates of the backlight modules for displaying in current mainstream products are substantially made in the non-printing manner via injection molding, i.e., via plastic injection molding, and the light guide plates are substantially acryl plate with a thickness of about 0.5-2.0 mm.
Currently, display devices are heading in a lighter and slimmer direction, and the backlight module is required in a similar way. And LED is gradually used in the backlight source. When a volume of the backlight source is reduced, the light guide plate has to be thinner before the display device may become slimmer. Generally, normal light guide plate has a thickness of about 1.0 mm. However, with the requirement from the market and by the technology, the thickness thereof is reduced gradually up to 0.5 mm. Due to the reduction of the thickness, some problems may be raised during manufacturing of the light guide plate. If conventional injection molding is adopted for forming the slim light guide plate, an injection molding machine with a high injection velocity may be required for forming a super slim light guide film. However, there is a strict surface quality requirement by the super slim light guide film. Therefore, a stricter requirement on temperature control and environment may be presented. For the conventional injection molding, yield and capacity problems may be raised to increase the cost accordingly if the light guide film with high quality may be manufactured. Currently, few countries are dedicated to the research on methods and processes for manufacturing super slim light guide film. For example, Japanese proposes an ink injection method for forming the light guide plate by injecting resin material from an ink injector to delineate on a lens, with a minimum thickness up to 50 um. However, diameters of dots formed in ink injecting manner are limited to 20-120 um, and the dots are substantially in microlens shape. And the groove configuration, depth and shape of the dots can hardly be varied.
In viewing thereof, there is an urgent need in obtaining a super slim light guide film with high quality, high yield rate and low cost etc.